Special Variables

Nushell makes available and uses a number of special variables and constants. Many of these are mentioned or documented in other places in this Book, but this page should include all variables for reference.

`$nu`

The $nu constant is a record containing several useful values:

default-config-dir: The directory where the configuration files are stored and read.
config-path: The path of the main Nushell config file, normally config.nu in the config directory.
env-path: The optional environment config file, normally env.nu in the config directory.
history-path: The text or SQLite file storing the command history.
loginshell-path: The optional config file which runs for login shells, normally login.nu in the config directory.
plugin-path: The plugin registry file, normally plugin.msgpackz in the config directory.
home-path: The user's home directory which can be accessed using the shorthand ~.
data-dir: The data directory for Nushell, which includes the ./vendor/autoload directories loaded at startup and other user data.
cache-dir: A directory for non-essential (cached) data.
vendor-autoload-dirs: A list of directories where third-party applications should install configuration files that will be auto-loaded during startup.
user-autoload-dirs: A list of directories where the user may create additional configuration files which will be auto-loaded during startup.
temp-path: A path for temporary files that should be writeable by the user.
pid: The PID of the currently running Nushell process.
os-info: Information about the host operating system.
startup-time: The amount of time (in duration) that it took for Nushell to start and process all configuration files.
is-interactive: A boolean indicating whether Nushell was started as an interactive shell (true) or is running a script or command-string. For example:
```
$nu.is-interactive
# => true
nu -c "$nu.is-interactive"
# => false

# Force interactive with --interactive (-i)
nu -i -c "$nu.is-interactive"
# => true
```
Note: When started as an interactive shell, startup config files are processed. When started as a non-interactive shell, no config files are read unless explicitly called via flag.
is-login: Indicates whether or not Nushell was started as a login shell.
history-enabled: History may be disabled via nu --no-history, in which case this constant will be false.
current-exe: The full path to the currently-running nu binary. Can be combined with path dirname (which is constant) to determine the directory where the binary is located.

`$env`

$env is a special mutable variable containing the current environment variables. As with any process, the initial environment is inherited from the parent process which started nu.

There are also several environment variables that Nushell uses for specific purposes:

`$env.config`

$env.config is the main configuration record used in Nushell. Settings are documented in config nu --doc.

`$env.PATH`

The search path for executing other applications. It is initially inherited from the parent process as a string, but converted to a Nushell list at startup for easy access.

It is converted back to a string before running a child-process.

`$env.ENV_CONVERSIONS`

Allows users to specify how to convert certain environment variables to Nushell types. See ENV_CONVERSIONS.

`$env.LAST_EXIT_CODE`

The exit code of the last command, usually used for external commands — Equivalent to $? from POSIX. Note that this information is also made available to the catch block in a try expression for external commands. For instance:

^ls file-that-does-not-exist e> /dev/null
$env.LAST_EXIT_CODE
# => 2

# or
try {
  ^ls file-that-does-not-exist e> /dev/null
} catch {|e|
  print $e.exit_code
}
# => 2

`$env.CMD_DURATION_MS`

The amount of time in milliseconds that the previous command took to run.

`$env.NU_VERSION`

The current Nushell version. The same as (version).version, but, as an environment variable, it is exported to and can be read by child processes.

`$env.CURRENT_FILE`

Inside a script, module, or sourced-file, this variable holds the fully-qualified filename. Note that this information is also available as a constant through the path self command.

`$env.FILE_PWD`

Inside a script, module, or sourced-file, this variable holds the fully qualified name of the directory in which the file resides. Note that this value is also available as a constant through:

path self | path dirname

`$env.PROCESS_PATH`

When executing a script, this variable represents the name and relative path of the script. Unlike the two variables above, it is not present when sourcing a file or importing a module.

Note: Also unlike the two variables above, the exact path (including symlinks) that was used to invoke the file is returned.